NeoGAF hosts a copy of the "trademark coexistence agreement" signed in late March, which lets both sides use the trademark as long as they don't get into each other's territory.
Microsoft will stay away from making a short-lived television show, while Fox will do its best not to make a new game in a franchise that hasn't seen a new installment since 1996.
This odd speed bump came up in September 2012 when Microsoft announced its intention to renew the trademark. Two months later, it became known that the trademark renewal was rejected due to Fox's trademark on the TV show. And no, it still doesn't mean a new Killer Instinct game is happening.